For example, in order to improve the system throughput and the user capacity in a service area in a LTE (Long Term Evolution) system, the use of HetNet (Heterogeneous Network) is considered. In the HetNet, micro base stations are arranged in such a manner as to be overlaid in a coverage of a macro base station. Further, by using the HetNet, a communication terminal communicating with a macro base station can be off-loaded to a micro base station. Therefore, by using the HetNet, the system throughput and the like can be improved.
In the HetNet environment, the coverage of the micro base station can be expanded by using CRE (Cell Range Expansion). More specifically, by using the CRE, a communication terminal adds an offset to a reception power of a signal transmitted from a micro base station. Accordingly, the area in which the communication terminal can connect to the micro base station is expanded, and as a result, the coverage of the micro base station is expanded. At this occasion, in particular, there is a problem in that a communication terminal located in an area expanded by CRE is affected by a higher level of interference caused by a signal transmitted from the macro base station. Therefore, in order to avoid the interference, an ABS (Almost Blank Subframe) which is a particular sub frame for controlling data transmission from the macro base station is used. For example, PTLs 1 and 2 disclose a configuration of a mobile communication network in which the interference caused by a signal transmitted from a macro base station is reduced in a micro base station by using ABS.